The invention relates to a method for producing a packing material from plastic film or a similar weldable material in the form of a bag or sack with side folds and a front and rear wall, which are connected at their two sides by side folds forming the side wall, and with a bottom, which, in turn, is connected with the front and rear walls as well as with the side folds, the front wall and the rear wall as well as the side walls in each case being formed from separate sections of material, which are connected together by welded seams.
Packing materials of the given type from plastic film or similar weldable material are known in numerous embodiments, which depend on the use, to which they are to be put, for example, as beverage bags, as refillable packages for liquid or pasty materials or generally as butt-ended bags for pourable materials of any type. Compared to such packing materials in the form of bags or sacks with side folds, which are formed from a single section of material, packing materials in the form of bags or sacks with side folds, for which the front and rear walls as well as the side walls in each case are formed from separate sections of material, offer greater freedom with respect to the design possibilities of the individual sections of material, particularly with regard to the printing of the packing material with sales-promoting information, information about goods and the like, as well as with regard to the length dimensions of the side folds forming the side walls, which need not necessarily be the same as the length or height of the packing material but, depending on the configuration of the head of the packing material corresponding to the use for which the packing material is to be put, can also be shorter than the height of the packing material or of unequal dimensions at the two sides of the packing material.
It is therefore an object of the invention to provide a method for producing a packing material from plastic film or a similar weldable material in the form of a bag or sack with side folds of the initially given type. Furthermore, it shall be possible to carry out the method simply and in a continuous process.
Pursuant to the invention, this objective is accomplished owing to the fact that material sections of the front wall and the rear wall are formed from a first and a second flat main sheet of material which, after a mutual overlapping is brought about, are conveyed in a first, common conveying direction, a third flat sheet of material is folded into a web with a side fold, severed from the side fold sections at a specified length and conveyed in a second direction transversely to the first conveying direction while resting on one of the two main sheets of material and that the bottom of the sack in turn is formed by a separate section of material of a fourth flat sheet of material, which is brought together with at least one of the two main sheets of material, then conveyed parallel to the first conveying direction and welded together with the side-fold sections as well as the two main sheets of material along their adjoining side edges. The possibility exists here of printing all the sheets of material, which are used in the inventive method, in continuous printing processes and to meet the length requirements of the side fold sections, forming the side walls, these requirements depending on the intended use for the packing material, as well as of using sheets of material, supplied continuously for the inventive method, a prerequisite for a continuous process, for which the individual steps of the method can be carried out with the material on a conveyor belt, until finally individual packing materials are severed from the sheets of material being worked on at the end of the process.
Numerous further distinguishing features and advantages of the invention arise out of the dependent claims and the description below of two examples of the inventive method, in conjunction with the accompanying drawings.